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Speaking of Diabetes is produced by Joslin Diabetes Center for people with diabetes and those who care for them..

Joslin Diabetes Center, a teaching and research affiliate of Harvard Medical School, is a one-of-a-kind institution on the front lines of the world epidemic of diabetes - leading the battle to conquer diabetes in all forms through cutting-edge research and innovative approaches to clinical care and education.

A new online weight loss calculator is getting some attention; it can tell you how long it will take to lose a specific amount of weight, how many calories you need to cut and/ or how much additional physical activity you have to engage in to reach your goal.

Now you may not think this isn’t too exciting since there are hundreds of calculators that will tell you the same thing. The interesting thing about this one (and it is embedded in the National Institute of Diabetes, Digestive and Kidney diseases website giving it heightened sense of credibility) is that it uses a different set of assumptions then many such computational devices.

The calculator was built on research conducted by Kevin Hall, MD and his group at the National Institute of Diabetes and Digestive and Kidney Diseases and originally published in the August 2011 edition of the Lancet. The calculator can be used both on an individual level and to evaluate the impact of public health strategies on calorie reduction in populations.

The usual way weight loss is calculated is to start with the premise that there are 3,500 calories in a pound and tell people by reducing between 250 and 500 calories a day from their usual intake they will lose 1 pound in 1 to 2 weeks (250 x 14 days or 500 x 7 days =3500 calories).

But reality rarely fits this model. The human body is engineered to preserve resources in the case of starvation, real or not, and adapts its metabolic rate to changing conditions. As weight is lost metabolism slows to retain energy stores.

In addition, as pounds drop off, the calorie expending benefits of physical activity go down. This is simply a consequence of it taking less energy to move a smaller mass (which is why people who have larger BMIs can cut the same amount of calories as someone with a smaller BMI, but lose weight faster in the short term).

In addition, the effects of physical activity on appetite are not consistent. Some people increase their intake in response to greater amounts of exercise while others consume less.

The body loses fat and lean tissue in parallel when you go on a weight loss diet. Unfortunately it takes about a 5-fold greater amount of energy to lose fat tissue than lean mass. And because lean mass contributes quite a bit more to energy expenditure than fat, the more fat you have over muscle, the longer it is going to take you to lose weight. That’s why resistancetrainingissoimportant to include in your exercise routine.

The mathematics behind the calculator are intricate and complex but the researchers provided the following rough and ready method for estimating how many calories you need to reduce to lose weight over the long haul: cut 10 calories a day for every pound of weight change desired. They estimate it will take about 3 years for most overweight people to lose all the weight they want to, with approximately 50 percent lost in the first year.

For example, if you need to lose 50 pounds, permanently cutting 500 calories a day would see you 25 pounds lighter by the end of the first year. If you kept it up, you would probably meet your target weight by year three.

The calculator has a 5 percent error rate based on the inability to predict initial energy needs accurately. Weight loss patterns will also differ based on day to day adherence to the calculations.

So if you want to see how much effort it will take to lose some weight give the calculator a try here.

Be sure to check with your doctor before making any major changes in diet or exercise plans!